Multistage DC coupled amplifier circuit a

Multistage DC coupled amplifier circuit a

 (3) Multi-stage DC-coupled amplifier circuit In a DC-coupled
amplifier circuit     composed of multi-stage amplifier circuits , if each stage uses an NPN transistor, in order to ensure that each stage has a suitable operating point, the base of the subsequent stage, The collector potential needs to be increased step by step, which reduces the variation range of the final output voltage. In order to solve this problem, in practical applications, NPN and PNP tubes can be used together to reduce the DC potential of the subsequent stage, as shown in the figure. Figure (8) shows that the NPN tube cvri)_ and the PNP tube (VT2) are used together to reduce the potential of the subsequent stage (VT3). In addition, emitter output devices, Zener diodes, etc. can also be used to reduce the DC potential of the subsequent amplifier circuit . Figure l-43 (b) shows the use of the emitter output device cvn) to reduce the potential of the subsequent stage (, rr3) .